This invention relates to communication network apparatus such as is used to link together information handling systems or computers of various types and capabilities and components of such apparatus. In particular, this invention relates to scalable switch apparatus and components useful in assembling such apparatus. This invention relates to an improved and multi-functional interface device and the combination of that device with other elements to provide a media speed network switch. The invention also relates to methods of operating such apparatus which improve the data flow handling capability of network switches.
The description which follows presupposes knowledge of network data communications and switches and routers as used in such communications networks. In particular, the description presupposes familiarity with the ISO model of network architecture which divides network operation into layers. A typical architecture based upon the ISO model extends from Layer 1 (also sometimes identified as “L1”) being the physical pathway or media through which signals are passed upwards through Layers 2, 3, 4 and so forth to Layer 7, the last mentioned being the layer of applications programming running on a computer system linked to the network. In this document, mention of L1, L2 and so forth is intended to refer to the corresponding layer of a network architecture. The disclosure also presupposes a fundamental understanding of bit strings known as packets and frames in such network communication.
In today's networked world, bandwidth is a critical resource. Increasing network traffic, driven by the Internet and other emerging applications, is straining the capacity of network infrastructures. To keep pace, organizations are looking for better technologies and methodologies to support and manage traffic growth and the convergence of voice with data.
Today's dramatic increase in network traffic can be attributed to the popularity of the Internet, a growing need for remote access to information, and emerging applications. The Internet alone, with its explosive growth in e-commerce, has placed a sometimes insupportable load on network backbones. It is also the single most important cause of increased data traffic volumes that exceed voice traffic for the first time. The growing demands of remote access applications, including e-mail, database access, and file transfer, are further straining networks.
The convergence of voice and data will play a large role in defining tomorrow's network environment. Currently, the transmission of data over Internet protocol (IP) networks is free. Because voice communications will naturally follow the path of lowest cost, voice will inevitably converge with data. Technologies such as Voice over IP (VoIP), Voice over ATM (VoATM), and Voice over Frame Relay (VOFR) are cost-effective alternatives in this changing market. However, to make migration to these technologies possible, the industry has to ensure quality of service (QoS) for voice and determine how to charge for voice transfer over data lines. The Telecommunications Deregulation Act of 1996 further complicates this environment. This legislation will reinforce a symbiotic relationship between the voice protocol of choice, ATM, and the data protocol of choice, IP.
Integrating legacy systems is also a crucial concern for organizations as new products and capabilities become available. To preserve their investments in existing equipment and software, organizations demand solutions that allow them to migrate to new technologies without disrupting their current operations.
Eliminating network bottlenecks continues to be a top priority for service providers. Routers are often the source of these bottlenecks. However, network congestion in general is often misdiagnosed as a bandwidth problem and is addressed by seeking higher-bandwidth solutions. Today, manufacturers are recognizing this difficulty. They are turning to network processor technologies to manage bandwidth resources more efficiently and to provide the advanced data services, at wire speed, that are commonly found in routers and network application servers. These services include load balancing,—QoS, gateways, fire walls, security, and web caching.
For remote access applications, performance, bandwidth-on-demand, security, and authentication rank as top priorities. The demand for integration of QoS and CoS, integrated voice handling, and more sophisticated security solutions will also shape the designs of future remote access network switches. Further, remote access will have to accommodate an increasing number of physical mediums, such as ISDN, T1, E1, OC-3 through OC-48, cable, and xDSL modems.
Industry consultants have defined a network processor (herein also mentioned as an “NP”) as a programmable communications integrated circuit capable of performing one or more of the following functions:                Packet classification—identifying a packet based on known characteristics, such as address or protocol        Packet modification—modifying the packet to comply with IP, ATM, or other protocols (for example, updating the time-to-live field in the header for IP)        Queue/policy management—reflects the design strategy for packet queuing, de-queuing, and scheduling of packets for specific applications        Packet forwarding—transmission and receipt of data over the switch fabric and forwarding or routing the packet to the appropriate address        
Although this definition is an accurate description of the basic features of early NPs, the full potential capabilities and benefits of NPs are yet to be realized. Network processors can increase bandwidth and solve latency problems in a broad range of applications by allowing networking tasks previously handled in software to be executed in hardware. In addition, NPs can provide speed improvements through architectures, such as parallel distributed processing and pipeline processing designs. These capabilities can enable efficient search engines, increase throughput, and provide rapid execution of complex tasks.
Network processors are expected to become the fundamental network building block for networks in the same fashion that CPUs are for PCs. Typical capabilities offered by an NP are real-time processing, security, store and forward, switch fabric, and IP packet handling and learning capabilities. NPs target ISO layer two through five and are designed to optimize network-specific tasks.
The processor-model NP incorporates multiple general purpose processors and specialized logic. Suppliers are turning to this design to provide scalable, flexible solutions that can accommodate change in a timely and cost-effective fashion. A processor-model NP allows distributed processing at lower levels of integration, providing higher throughput, flexibility and control. Programmability can enable easy migration to new protocols and technologies, without requiring new ASIC designs. With processor-model NPs, NEVs benefit from reduced non-refundable engineering costs and improved time-to-market.